if you have had any fecals done since you got him. There is always the chance that they can get parasites since they are eating live food. I would say that if color, eyes and skin look good that it could also be time of year. I have one male that gets real sluggish and stops eating in the winter. You would think he would starve but he perks up in the spring and does quite well.
I guess I would rule out any physical problems and keep offering different foods. If he isn't carrying parasites I would think he'll start eating again soon.
If things don't change, let us know and maybe we can come up with some ideas for you.